This has happened 1 time so far. Volvo can't find anything wrong with car. Diagnostics showed error codes for everything but yet once they unhooked car from machine it started right up and is running fine again. Air bag code and orange warning light were cleared but after 3 weeks they are back on again
I was driving on street 35mph. Car suddenly 'bucked', a 'thunk'sound came from it, then all power, electronics and engline died. Car was dead. I rolled into hard shoulder. No electrical power in car at all. After a few seconds i tried to start car, No power. Left car 5 mins, then car started, we went back on road, made it home turned car off waited 1 hour tried to start it and it would not start but had power back.
The Air bag code came on. and Orange Engine light came on.
Volvo cleared all the codes, said car ran fine. to stop the engine.
Volvo told me I may have to replace the CEM. (central Electronic module) if the engline dies again, but that is very expensive $1200.00.
Research on the web shows that many people with this make and model for 2004 are having the same issues